package main

import "fmt"

type Arr interface{
	Say() int
	Square() int
}

type Phone struct {

}

type REC struct{
	width,height int
}

var mobile Phone

func (p Phone)Say(){
	fmt.Println("Hello World")
}

func (rtf REC) Square(){
	fmt.Printf("%d\n",rtf.height*rtf.width)
}

func main(){
	mobile.Say()
	var r = REC{12,13}
	r.Square()
}